MEMS (microelectromechanical systems) were first created with conventional semiconductor tools. Specific requirements, such as dimensions, material sets, shapes led to the development of dedicated processes. This disconnect from the origins meant that the control integrated circuits (IC) could not be manufactured on the same substrates as the MEMS itself. Even though CMOS (complementary metal oxide semiconductor) compatible processes have been introduced enabling single-chip MEMS/IC, the wide majority of MEMS applications separates the sensor/actuator from the controller.
U.S. Pat. No. 7,242,089 discloses a silicon condenser microphone package which includes a transducer unit, a substrate, and a cover. The substrate includes an upper surface transducer unit attached to the upper surface of the substrate and overlapping at least a portion of a recess, wherein a back volume of the transducer unit is formed between the transducer unit and the substrate. A cover is placed over the transducer unit and either the cover or the substrate includes an aperture.
US 2012/0033846 discloses a method for fabricating flat loudspeakers comprising manufacturing a flat loudspeaker including at least one micro speaker array, having first and second main surfaces; and covering at least one of the main surfaces of the loudspeaker with a cover member including an airtight sound-pressure wave transparent thin polymer film.
With continuous demand for smaller form factors and improved performance at lower costs, there is still room for improved packaging solutions for heterogeneous integration.